British officials and media reacted with outrage after judges allowed terror suspect Abu Qatada, dubbed Osama bin Laden's right-hand man in Europe, to go free on bail Tuesday.
Monday's decision to uphold Abu Qatada's appeal against extradition to Jordan is a major blow for the British government, which has fought for years to deport the radical Islamist preacher.
London swiftly vowed to challenge the decision.
Government lawyer Robin Tam said Abu Qatada posed an "enormous" risk to national security and a risk of absconding and should be denied bail.
The Home Office said it "strongly disagrees" with the decision to grant Abu Qatada's appeal.
"We have obtained assurances not just in relation to the treatment of Qatada himself, but about the quality of the legal processes that would be followed throughout his trial," a spokesman said.
"We will therefore seek leave to appeal today's decision."
The British press slammed the decision, with The Daily Telegraph calling it "a mockery of justice".
"Yet again, the extremist cleric -- regarded as a serious threat to national security -- has exposed the limitations of the British state to decide who can and cannot stay within its borders," said its editorial.
Popular tabloid The Sun ran with front-page headline "Abu Hiss", a comment aimed at "soft judge" John Mitting, while the Daily Mirror carried the headline "Laughing in our faces" below a picture of the terror suspect.
The judges said there was a possibility that evidence obtained through torture could be used against Abu Qatada, a 51-year-old Jordanian of Palestinian origin, if he were sent back to face a retrial.
They announced that Abu Qatada, who has spent most of the last seven years in British jails fighting deportation, should be freed on bail on Tuesday.
The preacher was convicted in absentia in Jordan in 1998 of involvement in terror attacks.
Interior minister Theresa May had ordered Abu Qatada's extradition after she was given assurances by Jordan that no evidence gained through the torture of two other men would be used against him in a retrial.
But the Special Immigration Appeals Commission -- a semi-secret panel of British judges that deals with decisions on national security -- said those assurances could not be guaranteed.
"We are satisfied that the Secretary of State (May) should have exercised her discretion differently and should not have declined to revoke the deportation order," the commission said in its ruling.
"Accordingly, this appeal is allowed."
The judges agreed to free Abu Qatada on bail from the high-security Long Lartin jail in central England on condition that he observe a curfew for 16 hours a day and wear an electronic tag.
Arguing for bail, his lawyer Edward Fitzgerald told the court: "Enough is enough, it has gone on for many, many years now.
"There is no prospect of deportation taking place within a reasonable time, in fact there is no prospect at present of deportation at all."
The European Court of Human Rights had ruled earlier this year that Abu Qatada could not be deported while there was a "real risk that evidence obtained by torture will be used against him".
May then travelled to Jordan to secure guarantees from Amman that he would receive a fair trial and the European court subsequently gave the go-ahead for him to be extradited.
But the immigration tribunal's ruling Monday said statements from Abu Qatada's former co-defendants Al-Hamasher and Abu Hawsher, which were alleged to have been obtained by torture, created a risk that his trial would be unfair.
Al-Qaeda has threatened to attack Britain if it extradites Abu Qatada.
The cleric, a father of five who is also known as Omar Mohammed Othman, arrived in Britain in 1993 claiming asylum and has been a thorn in the side of successive British governments.
Videos of his sermons were found in the Hamburg flat used by some of the hijackers involved in the September 11, 2001 attacks. He has also defended the killing of Jews and attacks on Americans.
Britain first ordered his deportation in 2005 and his appeal against that order was rejected in 2009. May then signed a fresh deportation order and Abu Qatada appealed to the European Court of Human Rights.
He was briefly freed on bail earlier this year but then rearrested.
In October Britain extradited another radical Islamist preacher, Abu Hamza, and four other terror suspects to the United States at the end of a long legal battle.